It is estimated that roughly 90% of adults in the U.S. consume caffeine via food, drink, medication, or in some other form. Coffee especially has become a staple in the American diet. As many coffee drinkers know, each cup is part of a daily ritual that helps you get the most out of your day. But does this habitual behavior affect workout performance? Adding a cup or two before lunch, then a pre-workout supplement 30minutes before the gym can add up to roughly 400mgs of caffeine in one day. For comparison purposes, the most recent published study by Goncalves et al. would categorize a caffeine intake above 190mg as a “high” intake.3,4 Goncalves’ lab was examining how this elevated caffeine consumption might affect workout performance. Though caffeine has many variables to consider in any research design, there is significant increase to performance when consumed but no clear answers as to why. What then might be happening to our bodies when we consume caffeine and how does this chronic consumption affect your workout
Caffeine is one of the most well studied chemicals found in any diet though the abundant research hasn’t quite led to many conclusive statements on this drug. What has been discovered is that caffeine seems to exert its effects in muscle by three physiological methods. The first is by calcium release/absorption in muscle cells. Calcium is responsible for making binding sites available during muscle contraction. Therefore, more calcium released into the muscle means greater contractility or relaxation in the reverse scenario. The second method is through the inhibition of enzymes that break down cyclic Adenosine Mono Phosphate(cAMP). Inhibition of these enzymes increase the concentration of cAMP allowing for an environment whereby muscle cells can contract, increase calcium levels, and recover from different contractions (though this mechanism may need very high levels of caffeine in the plasma).2 The final mechanism is the antagonism of adenosine receptors which regulate glucose uptake, blood flow, in addition to muscle contraction. These three mechanisms can explain the performance benefits at the cellular level, but, there are other methods by which caffeine might act ergogenically.
Many coffee drinkers might be more familiar with the neurological effects of caffeine. Anecdotally one might feel an increase in energy levels, mental focus, alertness, among other positive - and addictive - sensations. Some research might acknowledge the neurological feeling but dispute the tangible effects. Just as many studies have shown no significant difference in reaction time, focus, alertness, etc. as those producing positive results.1 While you may feel mentally prepared for your workout or exam that feeling may not actually mean better results neurologically speaking. So, what exactly are you getting out of your caffeinated beverages if not that mental stimulus?
There is statistical evidence supporting the performance enhancing effects of caffeine consumed prior to the workout. This is not the case for all workout types, however. Performance benefits were observed when increasing endurance levels and overall repetitions in most cases.1 Overall power or strength tested by a one rep max did not elicit any improvements when caffeine was consumed prior to the workout.1,4 The reason why caffeine can improve endurance and not strength has eluded many researchers but a few theories have been proposed.
One factor may involve the stimulatory effect of caffeine on the adrenals. Adrenal glands are responsible for releasing the fight or flight chemicals into the blood (epinephrine and norepinephrine) or colloquially called adrenaline. Increasing adrenaline might help eke out a few more reps or a couple extra miles, though, exactly why this happens is still unknown. There is also a pain numbing effect to caffeine as well. The “runners-high” that many cross-country athletes experience is a sensation caused by endorphin release into the blood. Caffeine can also stimulate the release of endorphins and possibly help athletes fight through the pain a bit more easily.1 With so many physiological effects, does chronic caffeine intake – aka increased tolerance – reduce the benefits that world normally be seen in occasional consumers?
The Goncalves study recently reviewed by Dr. Eric Helms in the online journal MASS suggested the performance benefits of caffeine consumption are relevant despite a higher tolerance from chronic intake. Three levels of caffeine consumption were delineated as “low” (2-101mg), “moderate” (104-183mg), and “high” (190-583mg).3,4 Each group showed a significant increase in performance compared to the placebo. The degree to which caffeine increased performance however was not the same. Both the low and medium groups showed greater ergogenic effects than the higher intakes, though, the increase was slight.3,4 This might suggest chronic caffeine levels have a threshold where performance can level off or slightly decrease. One important caveat with this explanation is the generalization in caffeine intake categories. The high intake group has a much wider range of caffeine consumption which may affect the degree of significance. Another key consideration is the difference of performance between groups. When compared to each other the difference was not statistically significant meaning the ergogenic effect still exists even at the higher intakes.
Therefore, chronic caffeine intake still produces performance benefits but consuming too much may lessen the intensity of that boost. Most recommendations suggest roughly 2-3 cups per day or below 200mg to maximize the ergogenic effects (1-2mg/kg/day).4 Remember that this recommendation is a general guideline because so much about caffeine has yet to be understood. The physiological benefits at the cellular level and neurological processes can all change based on the individual. Variables like age, weight, genetics, medical history, medications, tolerance levels, stress, among many others all influence the effects of caffeine. And despite all potential variables some people can simply be “non-responders” further complicating the available research. Don’t get too overwhelmed, though, no matter the level of caffeine intake there is still some performance enhancing effect that can help power your workout just know the benefits lessen with each additional cup.
1. Anderson, D (2013). Caffeine. Sports Nutrition & Performance Enhancing Supplements. Ch 6. Linus Learning. Ronkonkoma, NY 11779. 2013.
2. Berdeaux, R. Stewart, R (2012). cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration. American Journal of Physiology - Endocrinology and Metabolism. July 2012. Vol. 303 no. 1. DOI:10.1152/ajpendo.00555.2011
3. Gonçalves, L. Painelli, V et al. (2017). Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation. Journal of Applied Physiology. July 2017. Vol. 123 no. 1, 213-220 DOI: 10.1152/japplphysiol.00260.2017
4. Helms, E (2017). Should I Stop Drinking Caffeinated Drinks So My Pre-Workout Works Better? Monthly Applications in Strength Sport (MASS). Issue 6. <https://www.massmember.com/products/mass-subscription/categories/340126/posts/1085223>